This program project application has as its central theme the idea that the cell cycle may provide targets that could be manipulated to alter the therapeutic outcome in cancer treatment. Assessing the validity of the this idea is totally dependent on the adequacy of the conditions used for the experimental assays. The most critical aspect of this is the cell synchrony and flow cytometry. Because adequate flow cytometry is central to all five projects, the decision has been made to centralize all flow analysis and have the bulk of the flow carried out by the most experienced team using a single facility. This ensures that all projects have access to the highest quality service and that the conditions and the form of analysis used throughout the entire project will be comparable. The team leader of this core, Dr. Bernard, is the most experienced scientist is QA aspects of flow cytometry and in synchronization procedures. The costs associated with core related to service center cost changed by the Cancer Center at the University of Pennsylvania for running flow samples. Additional funds have been requested to purchase a microcomputer and software for data analysis. Our experience is that the time available on the Cancer Center's computer for data analysis of large flow runs is frequently the bottleneck that prevents more rapid experimental progress. Frequently, the design of future experiments is dependent on having the analysis completed on previous runs. In time is unavailable for data analysis after data collection, it often results in part of the laboratory standing idle until the analysis is complete. Access to out own computer and software will eliminate this bottleneck.